Prof Rob Knight, from University of California San Diego, told the BBC, “You’re more microbe than you are human.” Interestingly, the human genome consists of 20,000 genes but if you add all the genes in our microbiome together, we have about two to 20 million microbial genes. Knight told the BBC, “We’re finding ways that these tiny creatures totally transform our health in ways we never imagined until recently.”

Prof Sarkis Mazmanian, a microbiologist from Caltech, told the BBC, “We don’t have just one genome, the genes of our microbiome present essentially a second genome which augment the activity of our own. What makes us human is, in my opinion, the combination of our own DNA, plus the DNA of our gut microbes.”